CASIMIR EFFECT AND RENORMALIZATION-GROUP

We discuss the Casimir energy (vacuum energy) for interaction theories , by means of renormalization (RG) methods. We find the RG improved va cuum energy for (i) QED between two plates, (ii) scalar electrodynamic s in De Sitter space, and (iii) a charged scalar field in a constant e lectromagnetic field. The relevance of the interaction, taken into acc ount via the RG improvement, is discussed for these examples. In parti cular, a numerical study of the improved vacuum energy in De Sitter sp ace (effective cosmological constant) gives the range of parameters fo r which the energy tends to zero.